The present invention relates to produce bags adapted for use on wicket pins of automatic produce packing machines.
Wicket produce bags have been developed for automatic produce packing machines. One portion of the bag has holes formed in it so that the bags can be suspended from wickets or pegs on an automatic packing machine. The earliest such bags were of polyethylene film.
Produce bags formed of a synthetic resin fabric mesh have been recently developed by the assignee of the present application, for example as described in U.S. patent application Ser. No. 08/888,175, filed Jul. 3, 1997, now U.S. Pat. No. 6,080,093. These bags were formed of a synthetic resin fabric mesh, such as the woven fabric of cross-laminated synthetic resin fibers known as Cross Laminated Airy Fabric or (CLAF) from Amoco Fabrics and Fibers, Inc. This fabric is an open mesh material of cross-laminated warp and weft strands or fibers of synthetic resin.
These types of bags are particularly useful for produce that must have access to fresh air to preserve the shelf life of the produce. However, when wicket holes are formed in this type of fabric mesh for automatic produce bag filling or packing machine purposes, problems have been found to occur. Slits were formed in the mesh in the area of the wicket holes leading away from the holes. The slits were formed in order to aid in tearing of the bag away from the packing machine once the bag was filled with product.
When the fabric mesh was slit for this purpose near the wicket holes, only a certain number of synthetic resin fiber strands in the fiber mesh were left uncut. The remaining uncut fiber strands were the sole support for the bag when it was suspended from the wicket rods or pegs and being filled with product. The number of strands left uncut was variable and indeterminate, and the reliability of the bags for use in automatic packing machines suffered. Bags with too many strands cut did not have adequate strength for use and would fall from the wickets during filling operations. Faulty bags could slow up operation of automatic packing machines by falling from the wickets when being filled with produce.
Composite bags formed of one synthetic resin mesh sheet and one synthetic resin film sheet have been proposed. So far as is known, however, the two sheets have been joined together along a common inner seam formed between the two walls at a bag bottom on or near the bottom portions of the sheets. The common inner seam was thus located to form the bottom of the contents holding portion of the bag. However, with this structure, problems have arisen, particularly with relatively large or comparatively heavy items such as potatoes or other produce. The weight and impact of these types of items as they were introduced during bag filling was received directly onto the seam joining the bag wall sheets together. Problems with breakage or rupture of the seams have occurred because of this. Further, bag filling operations have been disrupted and products for filling the bags spilled or wasted.
Briefly, the present invention provides a new and improved composite synthetic resin bag for use with wicket pins of automatic bag filling or packing equipment. The bag is formed of first and second side walls which are joined together along a bottom portion and two side edges. One of the side walls is formed from a cross-laminated synthetic resin fiber material mesh, such as a CLAF material or the like. The wall of mesh material forms a back or rear wall of the bag when placed on wicket pins of the equipment for product filling. The front or forward wall is formed of a synthetic resin film, such as polypropylene or polyethylene or the like. The fiber mesh side wall of the bag has a reinforcing strip of synthetic resin film extending along an upper edge. A wicket top is formed in the reinforcing strip for mounting the bag on the wicket pins of the bag packing machine or equipment. The reinforcing strip extends behind the rear mesh wall a length adequate to be brought into sealing contact with contact the front film bag wall and holding the rear mesh bag wall in firm engagement between the two resin film pieces.
The rear bag wall extends downwardly a certain predetermined length, but slightly less than the entire length of a completed bag. The front bag wall extends over a front face portion the entire length of a completed bag and in addition has a further downward extension. When the bag is assembled, the downward extension is folded upwardly against an outer surface of the fiber mesh rear bag wall. The fiber mesh bag wall and the upwardly folded film wall extension are joined together at a seam spaced upwardly from the folded synthetic resin bottom portion. The bag when assembled thus has a bottom portion which is formed entirely of a folded portion of synthetic resin film. The resin film has been found to be more elastic and thus resistant to impact and weight of produce as they enter the bag during packing.
It has been found that the fold of synthetic resin film exhibits greater strength during bag packing. Further, the seam between the fiber mesh wall and the film wall is spaced upwardly from the bottom of the bag and thus not directly subject to impact and weight of the product as it enters the bag during packing. An improved top corner seal structure is provided where the reinforcing strip and the front and rear side walls are joined. Bags according to the present invention exhibit greater strength in use during packing operations and are thus more reliable. Waste and damage to produce as a result of bags splitting at their bottom seams, either during loading or subsequent handling, are reduced with bags according to the present invention.